Development of a serial order in speech constrained by articulatory coordination.

Oohashi H, Watanabe H, Taga G - PLoS ONE (2013)

Bottom Line:
Furthermore, we reveal that serial order of different places of articulations within the same organ appears earlier and then gradually develops, whereas serial order of different articulatory organs appears later and then rapidly develops.In the same way, we also analyzed the sequences produced by English children and obtained similar developmental trends.These results suggest that the development of intra- and inter-articulator coordination constrains the acquisition of serial orders in speech with the complexity that characterizes adult language.

Affiliation: Graduate School of Education, The University of Tokyo, Tokyo, Japan ; Research Fellow of the Japan Society for the Promotion of Science, Koujimachi Business Center, Tokyo, Japan.

ABSTRACTUniversal linguistic constraints seem to govern the organization of sound sequences in words. However, our understanding of the origin and development of these constraints is incomplete. One possibility is that the development of neuromuscular control of articulators acts as a constraint for the emergence of sequences in words. Repetitions of the same consonant observed in early infancy and an increase in variation of consonantal sequences over months of age have been interpreted as a consequence of the development of neuromuscular control. Yet, it is not clear how sequential coordination of articulators such as lips, tongue apex and tongue dorsum constrains sequences of labial, coronal and dorsal consonants in words over the course of development. We examined longitudinal development of consonant-vowel-consonant(-vowel) sequences produced by Japanese children between 7 and 60 months of age. The sequences were classified according to places of articulation for corresponding consonants. The analyses of individual and group data show that infants prefer repetitive and fronting articulations, as shown in previous studies. Furthermore, we reveal that serial order of different places of articulations within the same organ appears earlier and then gradually develops, whereas serial order of different articulatory organs appears later and then rapidly develops. In the same way, we also analyzed the sequences produced by English children and obtained similar developmental trends. These results suggest that the development of intra- and inter-articulator coordination constrains the acquisition of serial orders in speech with the complexity that characterizes adult language.

pone-0078600-g007: The developmental curve of each fronting pattern in English.The black, gray and silver lines show developmental curves of the labial-vowel-coronal, labial-vowel-dorsal, and coronal-vowel-dorsal sequences, respectively. The circles, squares and triangles show raw fronting indices of the labial-vowel-coronal, labial-vowel-dorsal and coronal-vowel-dorsal sequences, respectively.

Mentions:
We analyzed the group data for English and obtained developmental curves of the repetitions (R2 = 0.525), the fronting tendencies (R2 = 0.301), the intra-organ articulations (R2 = 0.385) and the inter-organ articulations (R2 = 0.449 and 0.560 for labial-coronal and labial-dorsal patterns, respectively). The results showed a predominance of repetitions by around 12 months of age and gradually decreased within the range of the tracking periods (Figure 6i). The preferences to the fronting patterns initially increased and decreased at around 24 months (Figure 6ii). Note that, although previous studies reporting fronting tendencies mainly focus on only labial-coronal patterns [11], [12], this asymmetry was also observed in labial-dorsal and coronal-dorsal patterns (Figure 7). While the asymmetries of labial-coronal and labial-dorsal pattern persisted until 36 months, those of coronal-dorsal pattern declined to be around zero (Figure 7). As for the intra- and inter-organ articulations, we calculated durations of these developmental changes of them in the same way as was done for the analysis of Japanese. The durations of developmental change of intra-organ, labial-coronal inter-organ and labial-dorsal inter-organ were 15.6 (from 7.0 to 22.6), 5.9 (from 13.7 to 19.6) and 3.4 (from 14.0 to 17.4) months, respectively. These results also imply later presence and steeper development of the inter-articulatory temporal relationship than the intra-articulatory temporal relationship (Figures 6iii and 6iv).

pone-0078600-g007: The developmental curve of each fronting pattern in English.The black, gray and silver lines show developmental curves of the labial-vowel-coronal, labial-vowel-dorsal, and coronal-vowel-dorsal sequences, respectively. The circles, squares and triangles show raw fronting indices of the labial-vowel-coronal, labial-vowel-dorsal and coronal-vowel-dorsal sequences, respectively.

Mentions:
We analyzed the group data for English and obtained developmental curves of the repetitions (R2 = 0.525), the fronting tendencies (R2 = 0.301), the intra-organ articulations (R2 = 0.385) and the inter-organ articulations (R2 = 0.449 and 0.560 for labial-coronal and labial-dorsal patterns, respectively). The results showed a predominance of repetitions by around 12 months of age and gradually decreased within the range of the tracking periods (Figure 6i). The preferences to the fronting patterns initially increased and decreased at around 24 months (Figure 6ii). Note that, although previous studies reporting fronting tendencies mainly focus on only labial-coronal patterns [11], [12], this asymmetry was also observed in labial-dorsal and coronal-dorsal patterns (Figure 7). While the asymmetries of labial-coronal and labial-dorsal pattern persisted until 36 months, those of coronal-dorsal pattern declined to be around zero (Figure 7). As for the intra- and inter-organ articulations, we calculated durations of these developmental changes of them in the same way as was done for the analysis of Japanese. The durations of developmental change of intra-organ, labial-coronal inter-organ and labial-dorsal inter-organ were 15.6 (from 7.0 to 22.6), 5.9 (from 13.7 to 19.6) and 3.4 (from 14.0 to 17.4) months, respectively. These results also imply later presence and steeper development of the inter-articulatory temporal relationship than the intra-articulatory temporal relationship (Figures 6iii and 6iv).

Bottom Line:
Furthermore, we reveal that serial order of different places of articulations within the same organ appears earlier and then gradually develops, whereas serial order of different articulatory organs appears later and then rapidly develops.In the same way, we also analyzed the sequences produced by English children and obtained similar developmental trends.These results suggest that the development of intra- and inter-articulator coordination constrains the acquisition of serial orders in speech with the complexity that characterizes adult language.

Affiliation:
Graduate School of Education, The University of Tokyo, Tokyo, Japan ; Research Fellow of the Japan Society for the Promotion of Science, Koujimachi Business Center, Tokyo, Japan.

ABSTRACTUniversal linguistic constraints seem to govern the organization of sound sequences in words. However, our understanding of the origin and development of these constraints is incomplete. One possibility is that the development of neuromuscular control of articulators acts as a constraint for the emergence of sequences in words. Repetitions of the same consonant observed in early infancy and an increase in variation of consonantal sequences over months of age have been interpreted as a consequence of the development of neuromuscular control. Yet, it is not clear how sequential coordination of articulators such as lips, tongue apex and tongue dorsum constrains sequences of labial, coronal and dorsal consonants in words over the course of development. We examined longitudinal development of consonant-vowel-consonant(-vowel) sequences produced by Japanese children between 7 and 60 months of age. The sequences were classified according to places of articulation for corresponding consonants. The analyses of individual and group data show that infants prefer repetitive and fronting articulations, as shown in previous studies. Furthermore, we reveal that serial order of different places of articulations within the same organ appears earlier and then gradually develops, whereas serial order of different articulatory organs appears later and then rapidly develops. In the same way, we also analyzed the sequences produced by English children and obtained similar developmental trends. These results suggest that the development of intra- and inter-articulator coordination constrains the acquisition of serial orders in speech with the complexity that characterizes adult language.